Cotton cotyledon cDNA encoding a peroxidase

Plant Physiol. (1993) 102: 1351

Plant Gene Register

Cotton Cotyledon cDNA Encoding a Peroxidase' Darryl Ritter, Randy D. Allen, Norma Trolinder, D. Wayne Hughes, and Glenn A. Galau*

Department of Agronomy, Horticulture, and Entomology, Texas Tech University, Lubbock, Texas 79409 (D.R., R.D.A.); United States Department of Agriculture-Agricultura1 Research Service, Route 3, Box 215, Lubbock, Texas 79401 (N.T.); and Department of Botany, The University of Georgia, Athens, Georgia 30602-7271 (D.W.H., G.A.G.)

The location of this peroxidase is not known. However, it does not contain any of the carboxy-terminal sequences or topologies that are thought to direct proteins to targets other than the plasma membrane (Bednareket al., 1990; Chrispeels, 1991). Consequently, it is likely that this peroxidase functions in the cell wall.

The mRNA encoded by GrmM4 is highly induced in cotyledons two times during cotton (Gossypium hirsutum) embryo development and germination. It reaches a maximum concentration of about 1%of the total mRNA during the maturation stage, declines 6000-fold during the postabscission stage, and then again increases 1000-fold during the first 2 d of germination and seedling growth (Hughes and Galau, 1989). It is probably induced by different mechanisms during these two periods (Hughes and Galau, 1991). We report here that GrmM4 encodes a peroxidase (EC 1.11.1.7). Its mRNA is also present in roots and is induced 3-fold in young leaves of salt-stressed plants (D. Ritter, N. Trolinder, unpublished observations). The GrmM4 cDNA E39 from G. hirsutum L. cv Coker 201 (Hughes and Galau, 1989) was subcloned into pUC 19 and pBluescript and sequenced using externa1 and interna1 primers. It contains 1333 nucleotides and a poly(A) tail and encodes a peroxidase proprotein with a putative 23-amho acid signal sequence. The predicted mature protein is 35.1 kD, has an isoelectric point of 7.9, and contains the three peroxidase signature sequences at amino acid positions 49 to 64, 169 to 177, and 290 to 300, the eight Cys's involved in disulfide bridges, and the two His's involved with binding heme (Morgens et al., 1990).

Received February 1, 1993; accepted February 11, 1993. Copyright Clearance Center: 0032-0889/93/l02/1351/01. The GenBank accession number for the sequence reported in this article (GrmM4 cDNA E39) is L08199. LITERATURE ClTED

Bednarek SY, Wilkins TA, Dombrowski JE, Raikhel NV (1990) A carboxy-terminal propeptide is necessary for proper sorting of barley lectin to vacuoles of tobacco. Plant Cell 2: 1145-1155 Chrispeels MJ (1991) Sorting of proteins in the secretory system. Annu Rev Plant Physiol Plant Mo1 Biol42: 21-53 Hughes DW, Galau GA (1989) Temporally modular gene expression during cotyledon development. Genes Dev 3 358-369 Hughes DW, Galau GA (1991) Developmental and environmental induction of Leu and LeaA mRNAs and the postabscission program during embryo culture. Plant C e l l 3 605-618 Morgens PH, Callahan AM, Dunn LJ, Abels FB (1990) Isolation and sequencing of cDNA clones encoding ethylene-induced putative peroxidases from cucumber cotyledons. Plant Mo1 Biol 1 4 715-725

' Supported by grants from the National Institutes of Health to G.A.G. and the Texas High Technology Research Program to D.R. * Corresponding author; fax 1-706-542-1805.

Abbreviation: GrmM, gene expressed during both the maturation stage of embryogenesis and germination.

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